Grinding wheel and guard therefor



March 2, 1965 J. F. DE PAOL] 3,171,236

GRINDING WHEEL AND GUARD THEREFOR Filed April 16, 1962 gi /Mm United States Patent 3,171,236 GRINDING WHEEL AND GUARfi THEREFQR John F. De Paoli, 2604 Montrose Ave, Montrose, Calif.

Filed Apr. 16, 1962, Ser. No. 187,628

1 Claim. (ill. 51-209) This invention relates to the finishing of terrazzo or stone floors or like surfaces and more particularly to an improved grinding wheel and guard therefore for such finishing operations.

In the installation of terrazzo or comparable stone surfaces such as floors, steps, baseboards, and the like, various form of grinding machines are employed for producing a smooth surface thereon. All of such grinding machines use a cup type grinding wheel, the wheels being of different diameters according to the size of machine and the nature of the work for which it is intended. Where the floor or other surface being finished meets with a surface extending at an angle thereto, great care must be taken that the bordering surface be not marred by the side surface of the grinding wheel. Also, some machines for this finishing work employ a wheel carrying spindle mounted in a freely dirigible, head component adapted to be held by the operator, the spindle of which is connected to a driving motor by a flexible shaft. Both the torque reaction of the heavy flexible shaft incident to starting of the machine and the gyroscopie action of the rapidly rotating grinding wheel makes the head ditlicult to hold and this, in turn, invites trouble in working in close proximity to bordering surfaces and in the liability of the unguarded wheel to come into contact with a hand or other portion of the body of the user with resultant severe injury.

Numerous proposals to overcome these deficiencies have heretofore been made, and such proposals are usuly in the form of a stationary guard disposed adjacent to the side face of the grinding wheel. This, however, prevents machine finishing of a surface up to the bordering surface with the result that a strip is left for machine finishing with the guard removed at the very time the presence of guarding means is most needed. The alternative is, of course, a laborious and time consuming hand finishing operation for the strip thus left.

The present invention takes all of these deficiencies into account and has for its principal object the provision of a non-abrasive cover or coating effective to guide the side surface of a cup type grinding wheel such as employed for the Work above indicated.

Another object of the invention is to provide a guard means of the foregoing character which is attached to the grinding wheel by the means by which the grinding wheel is mounted on its operating spindle means.

A further object of the invention is to provide a wheel guard of the foregoing character which is abraded by contac with the surface being finished at the same rate that the working face of the grinding wheel is consumed incident to use.

Still another object of the invention is to provide a grinding wheel side surface guard of the foregoing character which is permanently aflixed to the side surface of the grinding wheel.

With the foregoing objects in view, together with such objects and advantages as may subsequently appear, the invention resides in the parts, and in the construction, combination and arrangement of parts described, by way of example, in the following specification of certain presently preferred embodiments of the invention, reference being had to the accompanying drawings which form a part of said specification and in which drawings:

FIG 1 is a side elevational View of a hand held head carrying a rotatable spindle and a grinding wheel mounted thereon and having guard means of one of the illustrated embodiments of the invention applied to the grinding wheel,

FIG. 2 is a top plan view of the head mechanism having reference to FIG. 1,

FIG. 3 is a bottom plan view of the head and wheel having reference to FIG. 1,

FIG. 4 is an enlarged scale, fragmentary sectional View taken on the staggered line 4-4 of FIG. 1,

FIG. 5 is an exploded perspective View of the grinding wheel, the mounting means therefor and guard means of the embodiment of the invention shown in the preceding figures,

FIG. 6 is a side elevational view, partly in section, of a grinding wheel for use in machines of the character for which the present invention is intended and having a guard means of another embodiment of the invention permanently afiixed to the side surface of the grinding wheel, and

FIG. 7 is a perspective view of the guard component of the embodiment of the invention shown in FIG. 6.

Referring first to FIGS. 1-5 of the drawings, there is shown a cup type grinding wheel 1 secured to a spindle 2 by a screw 3 extending first through the grinding wheel and then through a backup washer 4 and threadedly engaging a bore in the spindle 2. The spindle is journaled in a housing 5 and except for the wheel carrying end thereof is contained within the housing. Intermediate its ends, the portion of the housing 5 in which the spindle is journaled is provided with a laterally extending hearing portion or arm a to the free end of which the casing 7 of a flexible shaft (not shown) is connected; the shaft having a geared connection with the spindle within the housing for rotating the spindle from a power source connected to the opposite end of the flexible shaft. The housing 5 further is provided with an integrally formed, laterally extending handle 8 and with a port 9 at the end thereof remote from the wheel affording connection for a hose it) through which water is conducted to the surface of the wheel through axial bores extending through the spindle 2 and the screw 3, the bore in the spindle 2 having suitable connection with the port 9. All of the foregoing construction constitutes a common form of grinding apparatus for finishing surfaces of terrazzo or comparable material and to which apparatus the present invention is applied by way of example.

The first embodiment of the invention is shown in FIGS. l5 and comprises a shallow, dish-shaped, nonaorasive element Zll including a back portion 21 and a sidewall portion 22 engaging the side of the grinding wheel 1. The back portion 21 has a central hole 23 therein through which the mounting screw 3 extends to clamp said back portion between the back of the wheel and the backup washer 4- thus clamping the guard element in close association with the grinding wheel. This guard element is preferably formed of a tough and somewhat resilient plastic such as polyethylene or other plastic material having comparable, rubber-like charactertistics and being incapable of abrading either the surface being finished by the grinding wheel or an adjacent wall surface. This guard element rotates with the grinding wheel and the edge thereof adjacent the working face of the wheel will be worn away at the same rate that the face of the wheel is consumed in use. The non-abrasive character of the guard material will prevent the marring of any surface bordering the surface which is being finished with the grinding wheel, it being noted that the exterior of the face of the grinding wheel slopes slightly inwardly from the working face to the back thereof. This standard shaping of the grinding wheel permits the cover to contact a bordering surface only on a line contact closely adjacent to the working face of the wheel so that there is little, if any, danger that the bordering surface will be marred. Additionally, as the wheel is worn away through use, the decreasing diameter of this outer face and the guard carried thereby acts to present a guard surface which has not previously been subjected to wear through contact with the bordering surface.

Referring finally to FIGS. 6 and 7, there is shown av second embodiment of the invention in which the guard surface is formed as a frusto-conical band 30 which is adhesively or otherwise permanently secured to the peripheral surface of the grinding wheel 31. This guard element may be first formed and then secured to the grinding Wheel by suitable adhesives or it may be formed,

directly on the grinding Wheel by any appropriate process such as plastic molding in which the wheel is fitted into the mold as an insert in the plastic molding or in which the plastic is applied to the side surface of the wheel by a coating process as, for example, rotating the grinding wheel while maintaining a meniscus contact with the surface of a solution of the material employed for the guard coating. In this conneciton, it will be understood that the foreging reference to certain modes of manufacture are by Way of example and are not intended to imply that the manufacture of the guarded grinding wheel thus disclosed is limited to those methods. The function of this alternative form of guard element is the same as of the first described form.

While in the foregoing specification there have been disclosed certain presently preferred embodiments of the invention, the invention is not to be deemed to be limited to the precise details of construction thus disclosed by way of example and it will be understood that the invention includes as well all such changes and modications in the parts and in the construction, combination and arrangement of parts as shall come within the purview of the appended claim.

I claim:

The combination with a cup shaped grinding wheel for finishing terrazzo and comparable surfaces and having an axially disposed hole by which it is mounted on and secured to a driving spindle of a non-abrasive guard element overlying the outer periphery of said wheel; said guard element being formed of a tough, somewhat resilient, rubber-like material incapable of abrading either the surface being finished by the grinding wheel or an adjacent wall surface and having an edge coincident with the plane of the working face of the grinding wheel and being capable of being abraded to said plane as said working face is consumed in usage; said guard additionally including a back portion overlying the back surface of the grinding wheel and being provided with an axially disposed hole for reception of the driving spindle on which the grinding Wheel is mounted whereby said guard will be clamped between the back of the grinding wheel and the means on the spindle upon which the wheel is mounted.

References Cited by the Examiner UNITED STATES PATENTS 440,682 11/90 \Vood 51274 1,948,673 2/34 Reed 51-274 2,178,835 11/39 Hudson 5l-209 2,316,886 4/43 Pascucci 5l-177 2,800,754 7/57 Robertson 51-209 2,823,496 2/58 Winter 51267 3,016,662 1/62 Ellis 51-209 FOREIGN PATENTS 628,456 10/61 Canada.

LESTER M. SWINGLE, Primary Examiner.

FRANK H. BRONAUGH, JOHN C. CHRISTIE,

FRANK E. BAILEY, Examiners. 

